You can get a count of bills per month two ways:
1. You can see it in your billing statement: Its under Settings > Overview >Your Account with Us > Statements.
That shows a count of your free payments plus checks and epayments. That shows a count of each type of payment. You have to click on each statement to see it. The report shows payments but not total bills (it counts payments to the same vendor on the same day as one payment) so if you are looking for a complete count of bills paid, then...
2. You can get a report under the reports tab. The Bill Payments report can be done for any time period and it shows all bills paid. This can be done as html or csv file to make it easier to import into excel.